Multi-zone data converters

ABSTRACT

Aspects of a method and system for data converters having a transfer function with multiple operating zones. In some embodiments, an operating zone of the multiple operating zones is characterized by more stringent performance criteria than the other operating zones. Thus, such data converters may receive an input signal and generate an output signal from the input signal per the transfer function and the more stringent performance criteria in the appropriate operating zone.

CLAIM OF PRIORITY

This patent application makes reference to, claims priority to andclaims benefit from the U.S. Provisional Patent Application Ser. No.61/808,855, filed on Apr. 5, 2013. The above stated application ishereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

Certain embodiments of the invention relate to electronic circuits. Morespecifically, certain embodiments of the invention relate to methods andsystems for multi-zone data converters.

BACKGROUND

Existing data converters can be expensive and power hungry. Furtherlimitations and disadvantages of conventional and traditional approacheswill become apparent to one of skill in the art, through comparison ofsuch systems with some aspects of the present invention as set forth inthe remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for multi-zone data converters,substantially as shown in and/or described in connection with at leastone of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates an example electronic system that may be operable toperform digital-to-analog and analog-to-digital conversions.

FIGS. 2A and 2B are diagrams illustrating transfer characteristics ofexample multi-zone analog-to-digital converters.

FIGS. 3A and 3B are diagrams illustrating transfer characteristics ofexample multi-zone analog-to-digital converters.

FIG. 4 depicts an example multi-zone flash ADC in accordance withaspects of this disclosure.

FIG. 5 depicts an example multi-zone DAC in accordance with aspects ofthis disclosure.

FIG. 6 is a flow chart illustrating an example process fordesigning/configuring a multi-zone data converter.

DETAILED DESCRIPTION

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As usedherein, for example, a particular processor and memory may comprise afirst “circuit” when executing a first one or more lines of code and maycomprise a second “circuit” when executing a second one or more lines ofcode. As utilized herein, “and/or” means any one or more of the items inthe list joined by “and/or”. As an example, “x and/or y” means anyelement of the three-element set {(x), (y), (x, y)}. As another example,“x, y, and/or z” means any element of the seven-element set {(x), (y),(z), (x, y), (x, z), (y, z), (x, y, z)}. As utilized herein, the term“exemplary” means serving as a non-limiting example, instance, orillustration. As utilized herein, the terms “e.g.,” and “for example”set off lists of one or more non-limiting examples, instances, orillustrations. As utilized herein, circuitry is “operable” to perform afunction whenever the circuitry comprises the necessary hardware andcode (if any is necessary) to perform the function, regardless ofwhether performance of the function is disabled, or not enabled, by someuser-configurable setting.

Aspects of the invention include data converters customized for use insystems, such as communication systems, where much of the dynamic rangeof the data converters is present only to avoid clipping in the event ofinfrequent peaks (e.g., resulting from blocker signals). Because thesignals whose amplitudes range into the higher digital codes aretypically unwanted blocker signals, larger amounts of quantization noisemay be tolerable at such signal levels. Accordingly, the transferfunction of the data converters may be segmented into multiple zoneswith different zones having different characteristics (integralnonlinearity, differential nonlinearity, gain offset, and/or the like).For example, various components (e.g., comparators, resistors,capacitors, current sources, amplifiers, and/or the like) may havedifferent design constraints (e.g., size, power consumption, speed,impedance value matching in differential and/or switched capacitorcircuits, etc.) based on which bits of digital output code they areresponsible for generating.

FIG. 1 illustrates an example electronic system 100 that may be operableto perform analog-to-digital conversion and/or digital-to-analogconversion. The electronic system 100 may comprise suitable circuitry,interfaces, logic and/or code for implementing various aspects of thepresent disclosure. In this regard, the electronic system 100 may beconfigured to support performing, executing or running variousoperations, functions, applications and/or services. For example, theelectronic system 100 may be used for executing computer programs,playing video and/or audio content, gaming, communication applicationsor services (e.g., Internet access/browsing, email, text messaging,chatting and/or voice calling services), and/or networking services(e.g., WiFi hotspot, Bluetooth piconet, and/or active 3G/femtocell datachannels).

In some instances, the electronic system 100 may be configured to enableand/or support communication of data. In this regard, the electronicsystem 100 may communicate with other systems (local or remote), such asduring executing, running, and/or performing of operations, functions,applications and/or services supported by the electronic system 100. Forexample, the electronic system 100 may be configured to support (e.g.,using suitable dedicated communication components or subsystems) use ofwired and/or wireless connections/interfaces, which may be configured inaccordance with one or more supported wireless and/or wired protocols orstandards, to facilitate transmission and/or reception of signals(carrying data) to and/or from the electronic system 100. In thisregard, the electronic system 100 may be operable to process transmittedor received signals in accordance with applicable wired or wirelessprotocols.

Examples of wireless protocols or standards that may be supported and/orused by the communication subsystem 250 may comprise wireless personalarea network (WPAN) protocols, such as Bluetooth (IEEE 802.15); nearfield communication (NFC) standards; wireless local area network (WLAN)protocols, such as WiFi (IEEE 802.11); cellular standards, such as2G/2G+ (e.g., GSM/GPRS/EDGE, and IS-95 or cdmaOne) and/or 2G/2G+ (e.g.,CDMA2000, UMTS, and HSPA); 4G standards, such as WiMAX (IEEE 802.16) andLTE; Ultra-Wideband (UWB), direct broadcast satellite (DBS), microwavebackhaul, and/or the like. Examples of wired protocols and/or interfacesthat may be supported and/or used by the communication subsystem 250comprise Ethernet (IEEE 802.2), Fiber Distributed Data Interface (FDDI),Integrated Services Digital Network (ISDN), cable (DOCSIS) and UniversalSerial Bus (USB) based interfaces. Examples of signal processingoperations that may be performed by the electronic system 100 comprise,for example, filtering, amplification, analog-to-digital conversionand/or digital-to-analog conversion, up-conversion/down-conversion ofbaseband signals, encoding/decoding, encryption/decryption, and/ormodulation/demodulation.

In some instances, the electronic system 100 may be configured to enableor support input/output operations, such as to allow user interactionsthat may control services provided by the electronic system 100. In thisregard, the electronic system 100 may comprise components or subsystemsfor enabling interactions with a user (e.g., end-user or installer), soas to obtain user input and/or to provide user output.

The electronic system 100 may be a stationary system (i.e. beinginstalled at, and/or configured for use only in particular location). Inother instances, however, the electronic system 100 may be a mobiledevice—i.e., intended for use on the move and/or at different locations.In this regard, the electronic system 100 may be designed and/orconfigured (e.g., as handheld device) to allow for ease of movement,such as to allow it to be readily moved while being held by the user asthe user moves, and the electronic system 100 may be configured toperform at least some of the operations, functions, applications and/orservices supported on the move.

Examples of electronic systems may comprise handheld electronic devices(e.g., cellular phones, smartphones, or tablets), personal computers(e.g., laptops or desktops), servers, dedicated multimedia devices(e.g., televisions, game consoles, or portable media players), DBSoutdoor units, DBS indoor units (e.g., “set-top boxes”), microwavebackhaul outdoor units, microwave backhaul indoor units, or othersimilar receiver systems, and the like. The disclosure, however, is notlimited to any particular type of electronic system.

In operation, the electronic system 100 may be operable to performvarious operations, functions, applications and/or services. In thisregard, in some instances, performing the various, operations,functions, application or services supported by the electronic system100 may entail performing various processing operations on data handledby the electronic system 100. For example, communication of data,whether over wired or wireless interfaces, may typically comprisetransmitting and/or receiving analog signals that are communicated overwireless and/or wired connections. In this regard, typically analogradio frequency (RF) signals may be used to carry data (e.g., content),which may be embedded into the analog signals using analog or digitalmodulation schemes. For analog communications, data is transferred usingcontinuously varying analog signals, and for digital communications, theanalog signals are used to transfer discrete messages in accordance witha particular digitalization scheme.

Accordingly, handling of digital communications may typically requireperforming, among other things, digital-to-analog conversion (e.g., viaa digital-to-analog converter (DAC) 110) at the transmitting end andanalog-to-digital conversion (e.g., via a analog-to-digital converter(ADC) 120) at the receiving end. In this regard, the DAC 110 maycomprise circuitry, interfaces, logic and/or code for performingdigital-to-analog conversions and may implemented using various types ofDACs. For example, the DAC 110 may be implemented using a pulse-widthmodulator DAC, an oversampling DAC, interpolating DAC, a delta-sigmaDAC, binary-weight DAC, and R-2R ladder DAC, a successive-approximationDAC, a cyclic DAC, a thermometer-coded DAC, and/or a hybrid of one ormore of the previous DACs. Similarly, the ADC 120 may comprisecircuitry, interfaces, logic and/or code for performinganalog-to-digital conversions and may be implemented using various typesof ADCs. For example, the ADC 120 may be implemented using adirect-conversion ADC, a flash ADC, a successive-approximation ADC, aramp-compare ADC, a Wilkinson ADC, an integrating ADC, a dual-slope ADC,a multi-slope ADC, a delta-encoded ADC, a counter-ramp ADC, a pipelineADC, a subranging quantizer ADC, a sigma-delta ADC, a delta-sigma ADC, atime-interleaved ADC, etc.

In some electrical system 100, suitable performance of the electricalsystem 100 (e.g., measured in terms of signal to noise ratio, symbolerror rate, packet error rate, bit error rate, and/or some other metric)may require, or be more dependent upon, the data converter(s) (e.g., DAC110 and/or ADC 120) maintaining a high level of performance (measured interms of digital nonlinearity (DNL), integral nonlinearity (INL), gainoffset, and/or the like) in one or more ranges or zones of operation,but may not require, or may be less dependent upon, the dataconverter(s) maintaining a high level of performance in one or moreother ranges or zones of operation. In such situations, variousperformance criteria of the DAC 110 and/or the ADC 120 may be relaxed inoperations zones where lower performance has a lesser impact on theperformance of the electrical system 100. In this manner, the electricalsystem 100 may be able to achieve a level of performance typicallyassociated with use of high-end, high-cost data converters when usinglower-cost data converters that provide better performance in zones ofoperation having greater influence on the performance of the electricalsystem 100, but lesser performance in zones of operating having a lesserinfluence on the performance of the electrical system 100.

To this end, a transfer function of an example ADC 120 is shown in FIG.2A. As shown, a first zone Zone_(—)1 may range from analog input valueof 0 to V1 (in the example shown V1=2×VLSB, and VLSB is the voltagecorresponding to one least significant bit), a second zone Zone_(—)2 mayrange from an analog input value of V1 to V2 (V2=5*VLSB in the exampleshown), and a third zone Zone_(—)3 may range from an analog input valueof V2 to +VFS (full-scale)(where VFS=7*VLSB in the example shown). Forexample, the first zone Zone_(—)1 may be characterized by first integralnonlinearity INL_(—)1, the second zone Zone_(—)2 may be characterized bysecond integral nonlinearity INL_(—)2, and the third zone Zone_(—)3 maybe characterized by a third integral nonlinearity INL_(—)3. The secondintegral nonlinearity INL_(—)2 may be less than the first integralnonlinearity and may also be less than the third integral nonlineariINL_(—)2<INL_(—)1 and INL_(—)2<INL_(—)3).

Referring now to FIG. 2B, another transfer function for an example ADC120 is shown. As shown, the transfer function may include a first zoneZone_(—)1 that ranges from an analog input value of −VFS to −V1, asecond zone Zone_(—)2 that ranges from an analog input value of −V1 to+V1, and a third zone Zone_(—)3 that ranges from an analog input valueof +V1 to +VFS. Similar, to the transfer function of FIG. 2A,performance criteria (e.g., specified in terms of digital nonlinearity(DNL), integral nonlinearity (INL), gain offset, and/or the like) may berelaxed in the outer zones Zone_(—)1 and Zone_(—)3 and more stringent inthe central zone Zone_(—)2.

Thus, as shown in FIGS. 2A and 2B, an example ADC 120 may be implementedsuch that the second zone Zone_(—)2 achieves better performance (e.g.,measured in terms of digital nonlinearity (DNL), integral nonlinearity(INL), gain offset, and/or the like) than the first zone Zone_(—)1 andthe third zone Zone_(—)3. If performance of the second zone Zone_(—)2 ismore important to the performance of the electrical system 100 than theperformance of the first zone Zone_(—)1 and the third zone Zone_(—)3,then the electrical system 100 may be able to achieve an operatingperformance with such an ADC 120 that typically would require ahigher-cost ADC that performs as well in all zones as ADC 120 does inthe second zone Zone_(—)2.

FIGS. 3A and 3B illustrate example DAC transfer functions which exhibita multi-zone concept similar to the ADC transfer functions of FIGS. 2Aand 2B. In particular, a transfer function of an example DAC block 120is shown in FIG. 3A. As shown, a first zone Zone_(—)1 may range from adigital input code of 000 to 010, a second zone Zone_(—)2 may range froma digital input code 010 to 101, and a third zone Zone_(—)3 may rangefrom a digital input code of 101 to 111. The first zone Zone_(—)1 may becharacterized by first digital nonlinearity DNL_(—)1, the second zoneZone_(—)2 may be characterized by second digital nonlinearity DNL_(—)2,and the third zone Zone_(—)3 may be characterized by third digitalnonlinearity DNL_(—)3. The second digital nonlinearity DNL_(—)2 may beless than the first digital nonlinearity DNL_(—)1 and may be also lessthan the third digital nonlineari DNL_(—)2<DNL_(—)1 andDNL_(—)2<DNL_(—)3).

Referring now to FIG. 3B, another transfer function for an example DAC110 is shown. As shown, the transfer function may include a first zoneZone_(—)1 that ranges from a digital input code of 000 to 010, a secondzone Zone_(—)2 that ranges from a digital input code of 010 to 100, anda third zone Zone_(—)3 that ranges from a digital input code of 100 to110. Similar to the transfer function of FIG. 3A, performance criteria(e.g., specified in terms of digital nonlinearity (DNL), integralnonlinearity (INL), gain offset, and/or the like) may be relaxed in theouter zones Zone_(—)1 and Zone_(—)3 and more stringent in the centralzone Zone_(—)2.

Thus, as shown in FIGS. 3A and 3B, an example DAC 110 may be implementedsuch that the second zone Zone_(—)2 provides better performance (e.g.,measured in terms of digital nonlinearity (DNL), integral nonlinearity(INL), gain offset, and/or the like) than the first zone Zone_(—)1 andthe third zone Zone_(—)3. If performance of the second zone Zone_(—)2 ismore important to the performance of the electrical system 100 thanperformance of the first zone Zone_(—)1 and the third zone Zone_(—)3,then the electrical system 100 may be able to achieve an operatingperformance with such an DAC 110 that typically would require ahigher-cost DAC that performs as well in all zones as DAC 110 does inthe second zone Zone_(—)2.

The boundaries between zones (e.g., how low to set the split betweenZone_(—)1 and Zone_(—)2 and/or how high to set the split betweenZone_(—)2 and Zone_(—)3 in the previous examples) may be determinedbased on characteristics of signals to be processed by the dataconverters 110, 120. Performance criteria (e.g., INL, DNL, gain offset,and/or the like) for each zone of any given DAC or ADC may similarly bedetermined based on characteristics of signals to be processed by DAC orADC. For digitizing received communications signals, for example,highest performance (e.g., relatively low INL, relatively low DNL, andrelatively low gain offset) may be required of the mid-range digitalinput/output codes or analog input/output voltage values while lowerperformance (e.g., relatively high INL, relatively high DNL, and/orrelatively high gain offset) may be tolerated for low-range andhigh-range digital input/output codes or analog input/output voltagevalues. Thus, cost-savings may be achieved throughsimpler/smaller/faster/etc. circuitry used for processing the low-rangeand high-range signals, examples of which are described below withreference to FIGS. 4 and 5.

FIG. 4 depicts an example multi-zone flash ADC in accordance withaspects of this disclosure. The flash ADC 400 shown in FIG. 4 is anexample implementation of ADC 120 described above. In operation, eachcomparator 402 x (for 1≧×≧6) compares the input analog voltage to arespective reference voltage. The reference voltages increase as Xincreases. In an example implementation, comparators 402 ₁ and 402 ₂correspond to Zone_(—)1, comparators 402 ₃ and 402 ₄ correspond toZone_(—)2, and comparators 402 ₅ and 402 ₆ correspond to Zone_(—)3.Accordingly, performance criteria for the comparators 402 ₁, 402 ₂, 402₅, and 402 ₆ (e.g., gain, resolution, input offset, propagation delay,slew rate, and/or the like) may be relaxed as compared to theperformance criteria for comparators 402 ₃ and 402 ₄. This may enablethe comparators 402 ₁, 402 ₂, 402 ₅, and 402 ₆ to be smaller, consumeless power, have relaxed layout constraints, and/or the like as comparedto the comparators 402 ₃ and 402 ₄.

FIG. 5 depicts an example multi-zone DAC in accordance with aspects ofthis disclosure. The example DAC 500 is an example implementation of theDAC 110 described above. In operation, the value of the digital inputvalue determines which of the switches 504 ₁-504 ₇ are closed. For 000all switches 504 ₁-504 ₇ are open, for 001 switch 504 ₁ is closed andthe rest are open, for 010 switches 504 ₁ and 504 ₂ are closed and therest are open, and so forth. In an example implementation currentsources 502 ₁-502 ₄ and switches 504 ₁-504 ₄ correspond to a first zonethat requires high performance and current sources 502 ₅-502 ₇ andswitches 504 ₅-504 ₇ correspond to a second zone which can toleratedecreased performance. In such an implementation, the current sources502 ₅-502 ₆ may be lower cost (smaller, lower power consumption, lessaccurate matching, etc.) than current sources 502 ₁-502 ₄ and switches504 ₅-504 ₇ may be lower cost than switches 504 ₁-504 ₄ (e.g., switches504 ₁-504 ₄ may be transmission gates and switches 504 ₅-504 ₇ may besingle transistors).

FIG. 6 is a flow chart illustrating an example process fordesigning/configuring a multi-zone data converter. In block 604, afterstart block 602, a signal to be converted is characterized. This may bedone, for example, based on standard/protocols that govern the signaland/or based on characterization of the signal using test equipment. Foranalog-to-digital conversion, the characterization may comprise, forexample, generating a probability vs. analog input value graph or table.For digital-to-analog conversion, the characterization may comprise, forexample, generating a probability vs. digital input value graph ortable. In block 606, the number of operation zones of the converter, andboundaries between those zones, is determined. For example, usingdistinct transitions between areas of relatively high probability andareas of low probability may be mapped to boundaries between zones. Inblock 608, the converter is configured/designed to have the number ofzones and boundaries between zones determined in block 606. This mayinclude, for example, implementing relatively high performancecomponents (e.g., comparators, current sources, switches, etc.) for thehigh-probability zone(s) and relatively low performance components forthe low-probability zone(s). In block 610, the converter is used forconverting (A to D or D to A) the signal.

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the processes as described herein.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputing system, or in a distributed fashion where different elementsare spread across several interconnected computing systems. Any kind ofcomputing system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computing system with a program orother code that, when being loaded and executed, controls the computingsystem such that it carries out the methods described herein. Anothertypical implementation may comprise an application specific integratedcircuit or chip.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method, comprising: receiving an input signalwith a data converter; and generating, with the data converter, anoutput signal from the input signal per a transfer function, wherein thetransfer function comprises a plurality of operating zones, and whereina first operating zone of the plurality of operating zones ischaracterized by more stringent performance criteria than otheroperating zones of the plurality of operating zones.
 2. The method ofclaim 1, wherein: said receiving comprises receiving a digital inputcode from the input signal; and said generating comprises generating ananalog output value for the output signal that is dependent upon thereceived digital input code and the transfer function of the dataconverter.
 3. The method of claim 1, wherein: said receiving comprisesreceiving an analog input value from the input signal; and saidgenerating comprises generating a digital output code for the outputsignal that is dependent upon the received analog input value and thetransfer function of the data converter.
 4. The method of claim 1,wherein said generating comprises generating the output signal per themore stringent performance criteria of the transfer function in responseto receiving the input signal in the operating zone associated with themore stringent performance criteria.
 5. The method of claim 1, whereinsaid first operating zone characterized by more stringent performancecriteria corresponds to a central operating zone of the plurality ofoperating zones.
 6. The method of claim 5, wherein said generating theoutput signal per the more stringent performance criteria results in thedata converter generating the output signal with less digitalnonlinearity than output signals generated via the other operating zonesof the transfer function.
 7. The method of claim 1, wherein saidgenerating the output signal per the more stringent performance criteriaresults in the data converter generating the output signal with lessdigital nonlinearity than output signals generated via the otheroperating zones of the transfer function.
 8. The method of claim 5,wherein said generating the output signal per the more stringentperformance criteria results in the data converter generating the outputsignal with less analog nonlinearity than output signals generated viathe other operating zones of the transfer function.
 9. The method ofclaim 1, wherein said generating the output signal per the morestringent performance criteria results in the data converter generatingthe output signal with less analog nonlinearity than output signalsgenerated via the other operating zones of the transfer function. 10.The method of claim 1, wherein said generating the output signal per themore stringent performance criteria results in the data convertergenerating the output signal with less gain offset than output signalsgenerated via the other operating zones of the transfer function.
 11. Asystem, comprising: one or more circuits of a data converter, the one ormore circuits being operable to: receive an input signal; and generatean output signal from the input signal per a transfer function, whereinthe transfer function comprises a plurality of operating zones, andwherein a first operating zone of the plurality of operating zones ischaracterized by more stringent performance criteria than otheroperating zones of the plurality of operating zones.
 12. The system ofclaim 11, wherein said one or more circuits are operable to: receive adigital input code from the input signal; and generate an analog outputvalue for the output signal that is dependent upon the received digitalinput code and the transfer function.
 13. The system of claim 11,wherein said one or more circuits are operable to: receive an analoginput value from the input signal; and generate a digital output codefor the output signal that is dependent upon the received analog inputvalue and the transfer function.
 14. The system of claim 11, whereinsaid one or more circuits are operable to generate the output signal perthe more stringent performance criteria of the transfer function inresponse to receiving the input signal in the operating zone associatedwith the more stringent performance criteria.
 15. The system of claim11, wherein said first operating zone characterized by more stringentperformance criteria corresponds to a central operating zone of theplurality of operating zones.
 16. The system of claim 15, wherein saidone or more circuits are operable to generate the output signal per themore stringent performance criteria results in the output signal beinggenerated with less digital nonlinearity than output signals generatedvia the other operating zones of the transfer function.
 17. The systemof claim 11, wherein said one or more circuits are operable to generatethe output signal per the more stringent performance criteria results inthe output signal being generated with less digital nonlinearity thanoutput signals generated via the other operating zones of the transferfunction.
 18. The system of claim 15, wherein said one or more circuitsare operable to generate the output signal per the more stringentperformance criteria results in the output signal being generated withless analog nonlinearity than output signals generated via the otheroperating zones of the transfer function.
 19. The system of claim 11,wherein said one or more circuits are operable to generate the outputsignal per the more stringent performance criteria results in the outputsignal being generated with less analog nonlinearity than output signalsgenerated via the other operating zones of the transfer function. 20.The system of claim 11, wherein said one or more circuits are operableto generate the output signal per the more stringent performancecriteria results in the output signal being generated with less gainoffset than output signals generated via the other operating zones ofthe transfer function.